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Thread: Allow custom parameters with more than one dot in config files.

Allow custom parameters with more than one dot in config files.

From
Alexander Kukushkin
Date:
Hi hacker,

At the moment the only requirement for custom parameter names is that they should have one or more dots.
For example:
test5=# set a.b.c.d = 1;
SET
test5=# show a.b.c.d;
 a.b.c.d
---------
 1
(1 row)

But, Postgres fails to start if such parameters are set in the configuration file with the following error:
LOG:  syntax error in file "/tmp/cluster/postgresql.auto.conf" line 8, near token "a.b.c.d"
FATAL:  configuration file "postgresql.auto.conf" contains errors

What is more fun, ALTER SYSTEM allows writing such parameters to the postgresql.auto.conf file if they are defined in a session:
test5=# show a.b.c.d;
ERROR:  unrecognized configuration parameter "a.b.c.d"
test5=# alter system set a.b.c.d = 1;
ERROR:  unrecognized configuration parameter "a.b.c.d"
test5=# set a.b.c.d = 1;
SET
test5=# alter system set a.b.c.d = 1;
ALTER SYSTEM

In my opinion it would be fair to make parsing of config files with the rest of the code responsible for GUC handling by allowing custom parameters containing more than one dot.
The fix is rather simple, please find the patch attached.

Regards,
--
Alexander Kukushkin
Attachment

Re: Allow custom parameters with more than one dot in config files.

From
Tom Lane
Date:
Alexander Kukushkin <cyberdemn@gmail.com> writes:
> At the moment the only requirement for custom parameter names is that they
> should have one or more dots.
> ...
> But, Postgres fails to start if such parameters are set in the
> configuration file with the following error:

Hmm.

> In my opinion it would be fair to make parsing of config files with the
> rest of the code responsible for GUC handling by allowing custom parameters
> containing more than one dot.

I wonder if we wouldn't be better advised to require exactly one dot.
This isn't a feature that we really encourage users to use, and the
further we move the goalposts for it, the harder it will be to replace
it.  In particular I doubt the long-stalled session-variables patch
could support such names, since it needs the names to conform to
normal SQL rules.

            regards, tom lane

Re: Allow custom parameters with more than one dot in config files.

From
Alexander Kukushkin
Date:


On Tue, 19 Dec 2023 at 16:13, Tom Lane <tgl@sss.pgh.pa.us> wrote:

I wonder if we wouldn't be better advised to require exactly one dot.
This isn't a feature that we really encourage users to use, and the
further we move the goalposts for it, the harder it will be to replace
it.  In particular I doubt the long-stalled session-variables patch
could support such names, since it needs the names to conform to
normal SQL rules.

If I understand correctly, session variables don't even intersect with custom parameters.
Also, they seems to work fine with FQDN:
postgres=# create database testdb;
CREATE DATABASE
postgres=# \c testdb
You are now connected to database "testdb" as user "akukushkin".
testdb=# create schema testschema;
CREATE SCHEMA
testdb=# create variable testdb.testschema.testvar int;
CREATE VARIABLE
testdb=# let testdb.testschema.testvar = 1;
LET
testdb=# select testdb.testschema.testvar;
 testvar
---------
       1
(1 row)
 
Regards,
--
Alexander Kukushkin